whisper: clean up and integrate topics

whisper/message.go

@@ -75,8 +75,13 @@ func (self *Message) Wrap(pow time.Duration, options Options) (*Envelope, error)
 			return nil, err
 		}
 	}
+	// Convert the user topic into whisper ones
+	topics := make([]Topic, len(options.Topics))
+	for i, topic := range options.Topics {
+		topics[i] = NewTopic(topic)
+	}
 	// Wrap the processed message, seal it and return
-	envelope := NewEnvelope(options.TTL, options.Topics, self)
+	envelope := NewEnvelope(options.TTL, topics, self)
 	envelope.Seal(pow)
 
 	return envelope, nil